Functionality: A Web browser-based sandbox for front-end Web development, with markup options for Haml, Markdown, etc., stylesheet options for Sass, LESS or Stylus, and scripting options for JavaScript, CoffeeScript or LiveScript. Use for prototyping new ideas, reduced test cases for bugs, sending clients things to look at, evaluating potential hires, to finding inspiration. People also use CodePen as a sort of resume and portfolio, showing off their best design and development work.

System Requirements: Works on most web browsers.

Activities Supported:

Delivery Methods Supported: Supports writing and testing front-end code.

Subject Applicability: Computer Science

Security Concerns: None

Pricing Model: Free, but has 3 annual subscription options.